Hi
May I know if ChirpStack-Mesh supports Class C downlink?
Test Version:
Concentrator Version: 4.7.0
Gateway Mesh Version: 4.1.3
MQTT Forwarder Version: 4.5.1
chirpstack 4.16.2
I got these log message when the Class-C message had been queued.
Chirpstack-Mesh
May 25 21:27:23 OutdoorAP chirpstack-mqtt-forwarder[24125]: Received message, topic: eu868/gateway/00001c497bfb5e54/command/down, qos: AtMostOnce
May 25 21:27:23 OutdoorAP chirpstack-mqtt-forwarder[24125]: Received downlink command, downlink_id: 3110802898, topic: eu868/gateway/00001c497bfb5e54/command/down
May 25 21:27:23 OutdoorAP chirpstack-mqtt-forwarder[24125]: Sending downlink frame, downlink_id: 3110802898
May 25 21:27:23 OutdoorAP chirpstack-gateway-mesh[23948]: Downlink command received - [downlink_id: 3110802898 - [freq: 869525000, power: 29, mod: [LORA - sf: 12, bw: 125000], timing: [IMMEDIATELY]]]
May 25 21:27:23 OutdoorAP chirpstack-gateway-mesh[23948]: Handle command error: Only Delay timing is supported
May 25 21:27:23 OutdoorAP chirpstack-mqtt-forwarder[24125]: Received ack, items: [], downlink_id: 3110802898
May 25 21:27:23 OutdoorAP chirpstack-mqtt-forwarder[24125]: Sending ack event, downlink_id: 0, topic: eu868/gateway/00001c497bfb5e54/event/ack
Chirpstack
May 25 21:27:23 merryiot chirpstack[13214]: 2026-05-25T13:27:23.204641Z INFO schedule{dev_eui=2026052500000001 downlink_id=3110802898}: chirpstack::gateway::backend::mqtt: Sending downlink frame region_id=eu868 gateway_id=00001c497bfb5e54 topic=eu868/gateway/00001c497bfb5e54/command/down json=false
May 25 21:27:23 merryiot chirpstack[13214]: 2026-05-25T13:27:23.215852Z INFO chirpstack::gateway::backend::mqtt: Message received from gateway region_id="eu868" topic=eu868/gateway/00001c497bfb5e54/event/ack qos=AtMostOnce json=false
May 25 21:27:23 merryiot chirpstack[13214]: 2026-05-25T13:27:23.217623Z ERROR chirpstack::downlink::tx_ack: Handling tx ack error error=Zero items in tx ack
I've found that another person encountered this issue last year.
Gateway Mesh fails to relay downlinks to Class C devices.
Would it be possible to patch this solution into ChirpStack Mesh?
Thanks.